Air blower and control method thereof

ABSTRACT

When blowing out air, an air blower provides a user with feeling of being exposed to natural wind. A control unit of an air conditioner controls a fan motor of the air conditioner so that an airflow speed of a fan of the air conditioner changes over time with a synthesis pattern composed of a plurality of patterns including a sine-wave-like waveform pattern and a hill-like variation pattern having a width of less than a quarter cycle of the waveform pattern and a height of equal to or greater than an amplitude of the waveform pattern for each cycle of the waveform pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority from Japanese Patent Application No. 2012-175088, filed in Japan on Aug. 7, 2012, the content of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to an air blower and a control method thereof. The present invention relates to, in particular, an air conditioner that provides a user with feeling of being exposed to natural wind.

BACKGROUND ART

Conventionally, there is an air conditioner that makes vertical air vanes swing to provide air with fluctuation when the air is blown out (for instance, refer to Patent Literature 1). There is another air conditioner that controls a swing angle, a swing speed, and a swing range of vertical air vanes to 1/f fluctuation (for instance, refer to Patent Literature 2). There is another air conditioner, in which vertical air vanes are divided into three in the horizontal direction, and which makes the vertical air vanes swing so that phases of the angles of the central vertical air vane, and the left and right vertical air vanes could be different (for instance, refer to Patent Literature 3). There is another air conditioner, in which vertical air vanes are divided into two in the horizontal direction, and which makes the left and right vertical air vanes swing separately (for instance, refer to Patent Literature 4).

Further, there is another air conditioner that controls blowing air volume of an air blower to 1/f fluctuation (for instance, refer to Patent Literatures 5 and 6).

Further, there is an air blower that controls a revolution speed of a fan based on fuzzy inference (for instance, refer to Patent Literature 7).

CITATION LIST Patent Literature

Patent Literature 1: JP6-265168A

Patent Literature 2: JP10-110997A

Patent Literature 3: JP2001-108280A

Patent Literature 4: JP2007-132608A

Patent Literature 5: JP9-101807A

Patent Literature 6: JP 10-111004A

Patent Literature 7: JP7-151096A

SUMMARY OF INVENTION Technical Problem

According to the methods to make the vertical air vanes swing described in Patent Literatures 1 to 4, doldrums occur repeatedly at the user position. Further, the airflow speed hardly changes. Accordingly, it is impossible to reproduce natural wind which will be discussed later.

According to the methods to control the blowing air volume of the air blower to 1/f fluctuation as described in Patent Literatures 5 and 6, since the control is too fine, the fan motor might not be able to follow the control. The air delivered to the user might be, in fact, the air without airflow speed variation.

Even in the method to control the revolution speed of the fan based on the fuzzy inference as described in Patent Literature 7, it is also impossible to reproduce natural wind which will be discussed later.

The present invention aims to, for instance, provide a user with feeling of being exposed to natural wind when air is blown from an air blower.

Solution to Problem

An air blower according to one aspect of the present invention includes:

-   -   a fan blowing air;     -   a fan motor driving the fan; and     -   a control unit controlling the fan motor so that an airflow         speed of the fan changes over time with a synthesis pattern         composed of a plurality of patterns including a sine-wave-like         waveform pattern and a hill-like variation pattern having a         width of less than a quarter cycle of the waveform pattern and a         height of equal to or greater than an amplitude of the waveform         pattern for each cycle of the waveform pattern.

Advantageous Effects of Invention

According to one aspect of the present invention, a control unit of an air blower controls a fan motor of the air blower so that an airflow speed of a fan of the air blower changes over time with a synthesis pattern composed of a plurality of patterns including a sine-wave-like waveform pattern and a hill-like variation pattern having a width of less than a quarter cycle of the waveform pattern and a height of equal to or greater than an amplitude of the waveform pattern for each cycle of the waveform pattern, thereby providing the user with feeling of being exposed to natural wind.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will become fully understood from the detailed description given hereinafter in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of an air conditioner according to first and second embodiments.

FIG. 2 is a vertical cross-sectional view of the air conditioner according to the first and second embodiments.

FIG. 3 shows a drive mechanism of vertical air vanes and horizontal air vanes of the air conditioner according to the first and second embodiments.

FIG. 4 is a block diagram showing a configuration of a control system for a fan, the vertical air vanes, and the horizontal air vanes of the air conditioner according to the first and second embodiments.

FIG. 5 is a graph showing a sine wave which is a reference waveform for a revolution speed waveform of the fan of the air conditioner according to the first and second embodiments.

FIG. 6 is a graph showing the revolution speed waveform of the fan of the air conditioner according to the first embodiment.

FIG. 7 is a graph showing the revolution speed waveform of the fan of the air conditioner according to the second embodiment.

FIG. 8 is an enlarged graph showing a part of FIG. 7.

DESCRIPTION OF EMBODIMENTS

In describing a preferred embodiment illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of the present invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve a similar result.

Hereinafter, embodiments of the present invention will be explained with reference to the figures. Here, in the explanation of each embodiment, directions such as “top”, “bottom”, “left”, “right”, “front”, “rear”, “fore”, and “back” are used just for convenience; they are not to limit arrangement, direction, etc. of devices, apparatuses, components, etc.

Embodiment 1

FIG. 1 is a perspective view of an air conditioner 100 according to the present embodiment. FIG. 2 is a vertical cross-sectional view of the air conditioner 100.

As shown in FIGS. 1 and 2, the air conditioner 100 includes a main body 101 of an indoor unit, a fan 102, a pre-filter 103, a front panel 104, a first heat exchanger 105 a, a second heat exchanger 105 b, a third heat exchanger 105 c, a fourth heat exchanger 105 d, a drain pan 106, vertical air vanes 107, horizontal air vanes 108, and a sensor 109.

The main body 101 is formed substantially into a horizontally long cuboid. The fan 102, the pre-filter 103, the first heat exchanger 105 a, the second heat exchanger 105 b, the third heat exchanger 105 c, and the fourth heat exchanger 105 d are contained inside the main body 101. An air inlet 110 is provided at a top face of the main body 101. An air outlet 111 is provided at a lower part of a front face of the main body 101. The vertical air vanes 107 and the horizontal air vanes 108 are attached to the air outlet 111. The sensor 109 is mounted at the front face of the main body 101, a little above the air outlet 111. The front panel 104 is attached at the front face of the main body 101 so as to be openable and closable. An opening part is formed at a part of the front panel 104 corresponding to the sensor 109, so that the sensor 109 is not covered even when the front panel 104 is closed. The drain pan 106 is provided below the first heat exchanger 105 a, the second heat exchanger 105 b, the third heat exchanger 105 c, and the fourth heat exchanger 105 d.

The fan 102 sucks indoor air from the air inlet 110 to the inside of the main body 101. The pre-filter 103 removes powder dust, etc. contained in the sucked air. The first heat exchanger 105 a, the second heat exchanger 105 b, the third heat exchanger 105 c, and the fourth heat exchanger 105 d carry out heat exchange between the air and refrigerant passing through the inside. The fan 102 blows out the heat-exchanged air from the air outlet 111 to the outside of the main body 101 (i.e., the inside of a room). That is, the fan 102 blows the air to the inside of the room. The direction of the air blown out from the air outlet 111 is adjusted by the vertical air vanes 107 and the horizontal air vanes 108.

The vertical air vanes 107, having a cross section of a substantially arc shape, are provided so as to be swingable. The vertical air vanes 107 adjust the vertical direction of the air blown out from the air outlet 111 (i.e., the airflow from the fan 102). The vertical air vanes 107 are divided at a substantially central part of the main body 101 in the longitudinal direction (i.e., the horizontal direction of the air outlet 111) into a left vertical air vane 107 a and a right vertical air vane 107 b. The left vertical air vane 107 a and the right vertical air vane 107 b are arranged at the air outlet 111 with a slight interval.

The horizontal air vanes 108, being substantially tabular, are provided so as to be swingable. The horizontal air vanes 108 adjust the horizontal direction of the air blown out from the air outlet 111 (i.e., the airflow from the fan 102). The horizontal air vanes 108 include left horizontal air vanes 108 a located at the left side of the substantially central part of the main body 101 in the longitudinal direction (i.e., the horizontal direction of the air outlet 111) and right horizontal air vanes 108 b located at the right side of the substantially central part. The left horizontal air vanes 108 a and the right horizontal air vanes 108 b are respectively divided into plural pieces and arranged at the air outlet 111.

The sensor 109 detects a position where a human body exists, inside the room. The sensor 109 is, for instance, an infrared sensor in which thermopiles are vertically aligned. Thermal image of the inside of the room can be obtained by moving the thermopiles laterally to scan the inside of the room. In the thermal image, a position where a human body exists can be detected in the lateral and the depth directions by the temperature difference from the background. The larger the number of pixels of the thermal image is, the more accurately the position of the human body can be detected. The number of pixels is desired to be equal to or greater than 700 pixels, which enables sufficiently accurate detection of the position of the human body. Here, the sensor 109 is not limited to the infrared sensor, but may be a camera, a pyroelectric sensor using Fresnel lens, etc. Further, the sensor 109 may not be mounted at the front face of the main body 101, and may instead be mounted at a left end or a right end of the main body 101.

FIG. 3 shows a driving mechanism of the vertical air vanes 107 and the horizontal air vanes 108.

As shown in FIG. 3, the vertical air vanes 107 include one left vertical air vane 107 a and one right vertical air vane 107 b. The left vertical air vane 107 a is linked to a stepping motor 113 a by a link rod 112 a. The stepping motor 113 a rotates the link rod 112 a, thereby changing an angle of the left vertical air vane 107 a. Similarly, the right vertical air vane 107 b is linked to a stepping motor 113 b by a link rod 112 b. The stepping motor 113 b rotates the link rod 112 b, thereby changing an angle of the right vertical air vane 107 b.

The horizontal air vanes 108 include eight left horizontal air vanes 108 a and eight right horizontal air vanes 108 b. The left horizontal air vanes 108 a are arranged with substantially equal intervals. The left horizontal air vanes 108 a are all linked to a stepping motor 115 a by a link rod 114 a. The stepping motor 115 a rotates the link rod 114 a, thereby changing angles of the left horizontal air vanes 108 a all at once. Similarly, the right horizontal air vanes 108 b are arranged with substantially equal intervals. The right horizontal air vanes 108 b are all linked to a stepping motor 115 b by a link rod 114 b. The stepping motor 115 b rotates the link rod 114 b, thereby changing angles of the right horizontal air vanes 108 b all at once.

FIG. 4 is a block diagram showing a configuration of a control system for the fan 102, the vertical air vanes 107, and the horizontal air vanes 108.

As shown in FIG. 4, the air conditioner 100 further includes a fan motor 116, a communication unit 117, and a control unit 118.

The fan motor 116, which is contained inside the main body 101, drives the fan 102.

The communication unit 117 is provided at, for instance, the lower part of the front face of the main body 101 and receives signals from an external remote control 120.

The control unit 118, which is contained inside the main body 101, is implemented by, for instance, a microcomputer. The control unit 118 is connected to the sensor 109, the stepping motors 113 a, 113 b, 115 a, and 115 b, the fan motor 116, the communication unit 117, and other various units via signal lines. The control unit 118 receives various information via the signal lines and controls the operation of the air conditioner 100 based on the received information.

In the present embodiment, the control unit 118 controls the fan motor 116 so that airflow similar to natural wind is blown out from the air outlet 111 by the fan 102.

Through observation of natural wind, the following characteristics of natural wind are found:

(Characteristic 1) Natural wind is not such an intermittent wind that is blown out by the conventional air conditioner which makes vertical air vanes swing. Even in so-called doldrums, natural wind speed goes up and down in the vicinity of 0.2 m/s (meters per second), at which a human feels the wind. That is, there exist no complete doldrums. (Characteristic 2) A moving average of natural wind speed is a sine wave having a constant periodicity. Specifically, it is a sine wave having a cycle of around 100 to 200 seconds. (Characteristic 3) As for a waveform of natural wind speed, a wave having a wide width and a high height occurs once or some times in around 10 to 60 seconds. The height of this wave is sometimes slightly lower. That is, there mixedly exist a slightly high wave and a high wave. (Characteristic 4) As for the waveform of natural wind speed, there frequently occurs a wave having a narrow width and a low height. The height of this wave is approximately the same every time.

In the present embodiment, the control unit 118 continuously changes the revolution speed of the fan 102 so that the fan 102 delivers airflow having at least the characteristics of the above (Characteristic 1) to (Characteristic 3) at the time of cooling operation or air-blowing operation of the air conditioner 100.

FIG. 5 is a graph showing a sine wave 131 which is a reference waveform for a revolution speed waveform of the fan 102.

As described above, the moving average of natural wind speed is a sine wave having a cycle of around 100 to 200 seconds. As shown in FIG. 5, the control unit 118 controls the fan motor 116 so that the gradual sine wave 131 having the cycle of 120 seconds is the reference waveform for the revolution speed waveform of the fan 102.

As described above, even in so-called doldrums, natural wind speed goes up and down in the vicinity of 0.2 m/s. When the revolution speed of the fan 102 is 800 rpm (revolutions per minute), the airflow speed measured at a position which is 3 meters in front of the air conditioner 100 is around 0.2 m/s. It is considered this position is a standard user position. In the present embodiment, the control unit 118 controls the fan motor 116 so that an average revolution speed of the fan 102 is 800 rpm in one cycle, and the sine wave 131, of which a variation range of the revolution speed of the fan 102 in one cycle is smaller than the average revolution speed, is the reference waveform. The maximum revolution speed of the fan 102 in one cycle is 900 rpm, the minimum revolution speed is 700 rpm, and the variation range, which is a difference between the maximum revolution speed and the minimum revolution speed, is 200 rpm.

In the present embodiment, the variation range of the revolution speed of the fan 102 is small in one cycle of the sine wave 131. Therefore, as will be discussed later, when a wave component having a wide width and a high height is synthesized to the sine wave 131, the user can clearly feel the airflow corresponding to the wave component.

Here, it is not essential that the cycle of the sine wave 131 is 120 seconds. The cycle may be any cycle as long as it is around 100 to 200 seconds.

It is not also essential that the average revolution speed of the fan 102 is 800 rpm. The average revolution speed of the fan 102 is not limited to be fixed but may be changeable.

It is not also essential that the variation range of the revolution speed of the fan 102 is 200 rpm. The variation range may be any range as long as it is smaller than the average revolution speed of the fan 102.

FIG. 6 is a graph showing the revolution speed waveform of the fan 102.

As described above, as for the waveform of natural wind speed, the wave having a wide width and a high height occurs once or some times in around 10 to 60 seconds. The height of this wave is sometimes slightly lower. As shown in FIG. 6, the control unit 118 controls the fan motor 116 so that first peak waves 141, each having a width of around 5 to 10 seconds and a height (i.e., the peak value) of around 200 rpm, and second peak waves 142, each having a width of around 10 to 20 seconds and a height (i.e., the peak value) of around 100 rpm, are synthesized to the sine wave 131. The first peak waves 141 are synthesized to the sine wave 131 at the time points of around 30 seconds, around 70 seconds, and around 110 seconds in one cycle of the sine wave 131. The second peak waves 142 are synthesized to the sine wave 131 at the time points of around 60 seconds and around 90 seconds in one cycle of the sine wave 131.

If the height of the first peak waves 141 and the second peak waves 142 are lower than the amplitude of the sine wave 131, the airflow speed seldom changes, and thus the user cannot easily obtain the feeling of being exposed to natural wind. In the present embodiment, the height of the first peak waves 141 and the second peak waves 142 are around 200 rpm and around 100 rpm, respectively, and the amplitude of the sine wave 131 (i.e., a half of the variation range of the revolution speed of the fan 102) is 100 rpm. Namely, the height of the first peak waves 141 and the second peak waves 142 are equal to or greater than the amplitude of the sine wave 131. Therefore, the momentary airflow speed variation which can be clearly sensed by the user is given to the airflow from the fan 102, thereby improving the comfort.

The control unit 118 stores a table specifying targeted revolution speeds of the fan 102 in an embedded memory. The control unit 118 supplies a command voltage to the fan motor 116 based on the table, thereby continuously changing the revolution speed of the fan 102.

The table contains data specifying the targeted revolution speed of the fan 102 for each unit time. The table, as a whole, contains one-cycle data of the sine wave 131. Since one cycle is 120 seconds, if it is assumed that the targeted revolution speed is specified for every 0.25 seconds, the number of pieces of data is 480. Or, if it is assumed that the targeted revolution speed is specified for every 0.5 seconds, the number of pieces of data is 240. When one unit time is too short, the fan motor 116 cannot follow the control, and thus the intended airflow cannot be delivered to the user. Further, the data quantity to be contained increases, and thus the capacity of the memory becomes tight and the cost rises. Therefore, it is desirable to set one unit time to equal to or greater than 0.1 seconds, with which the fan motor 116 is considered to be able to certainly follow the control.

In the present embodiment, the sine wave 131 is the reference waveform for the revolution speed waveform of the fan 102, and the first peak waves 141 each having a wide width and a high height and the second peak waves 142 each having a wide width and a slightly high height are synthesized to the sine wave 131. In order to make the moving average of the airflow speed of the fan 102 equal to the sine wave 131 or close to the sine wave 131 similarly to the natural wind speed, it is desirable to make the width of the first peak waves 141 and the second peak waves 142 as short as possible compared with one cycle of the sine wave 131. Since the peak waves, which are either of the first peak waves 141 and the second peak waves 142, occur at least once in around 10 to 60 seconds, the width of each of the peak waves is set to less than a quarter cycle, and more preferably, less than a ⅛ cycle of the sine wave 131.

If the user is exposed to a strong airflow continuously, the user may have feeling of repulsion, and dryness of the user's skin may be accelerated. However, since the airflow corresponding to the peak waves blows only momentarily, the user will never be exposed to the strong airflow continuously. Therefore, the comfort is improved. Further, the user can obtain the feeling of being exposed to natural wind.

However, if the time during which each of the peak waves maintains the peak value is too short, the user hardly feels the airflow corresponding to the peak waves. Therefore, it is desirable to set the time during which each of the peak waves maintains the peak value to equal to or greater than two unit times, with which the user is considered to be able to clearly feel the airflow corresponding to the peak waves.

Assuming that the time during which each of the peak waves maintains the peak value is set to only one unit time, only one piece of data specifying a peak targeted revolution speed is contained between data specifying a pre-peak targeted revolution speed and data specifying a post-peak targeted revolution speed, in the table stored in the memory. Reading the data specifying the pre-peak targeted revolution speed, the control unit 118 controls the fan motor 116 so that the pre-peak targeted revolution speed and the revolution speed of the fan 102 match. Next, reading the data specifying the peak targeted revolution speed, the control unit 118 controls the fan motor 116 so that the peak targeted revolution speed and the revolution speed of the fan 102 match. However, when the difference between the pre-peak targeted revolution speed and the peak targeted revolution speed is large, the fan motor 116 cannot follow the control, and thus the revolution speed of the fan 102 might not reach the peak targeted revolution speed. Even if the revolution speed of the fan 102 does not reach the peak targeted revolution speed, the control unit 118 next reads the data specifying the post-peak targeted revolution speed, and controls the fan motor 116 so that the post-peak targeted revolution speed and the revolution speed of the fan 102 match. As a result, the revolution speed of the fan 102 becomes the post-peak targeted revolution speed directly from the pre-peak targeted revolution speed, and thus the peak air volume might not be obtained. When the peak air volume cannot be obtained, only the pre-peak and post-peak airflows having relatively low speed are delivered to the user.

On the other hand, if the time during which each of the peak waves maintains the peak value is set to equal to or greater than two unit times, two or more pieces of the data specifying the same peak targeted revolution speed are contained between the data specifying the pre-peak targeted revolution speed and the data specifying the post-peak targeted revolution speed, in the table stored in the memory. Reading the data specifying the pre-peak targeted revolution speed, the control unit 118 controls the fan motor 116 so that the pre-peak targeted revolution speed and the revolution speed of the fan 102 match. Next, reading the first piece of the data specifying the peak targeted revolution speed, the control unit 118 controls the fan motor 116 so that the peak targeted revolution speed and the revolution speed of the fan 102 match. Even if the revolution speed of the fan 102 does not reach the peak targeted revolution speed, the control unit 118 next reads the subsequent piece(s) of data specifying the peak targeted revolution speed, and continues to control the fan motor 116 so that the peak targeted revolution speed and the revolution speed of the fan 102 match. As a result, the revolution speed of the fan 102 reaches the peak targeted revolution speed, and thus the peak air volume can certainly be obtained.

Here, the time during which each of the peak waves maintains the peak value may be set to, instead of equal to or greater than two unit times, equal to or greater than 0.5 seconds. If the time during which each of the peak waves maintains the peak value is set to less than 0.5 seconds, the fan motor 116 cannot follow the control, and the peak air volume might not be obtained. On the other hand, if the time during which each of the peak waves maintains the peak value is set to equal to or greater than 0.5 seconds, the control unit 118 continues, for equal to or greater than 0.5 seconds, to control the fan motor 116 so that the peak targeted revolution speed and the revolution speed of the fan 102 match. As a result, even if the fan motor 116 cannot follow the control at first, the revolution speed of the fan 102 finally reaches the peak targeted revolution speed, and thus the peak air volume can certainly be obtained. If the time during which each of the peak waves maintains the peak value is set to equal to or greater than 1.0 second, the peak air volume can be obtained more certainly.

If the time during which each of the peak waves maintains the peak value is set to equal to or greater than two unit times, and equal to or greater than 0.5 seconds, the peak air volume can be obtained even more certainly.

If there is only one type of the peak waves, the user may get used to the airflow from the fan 102, and thus the comfort might be lost. However, if there are equal to or greater than two types of the peak waves, the user does not get used to the strong airflow which comes once in a while, and thus the comfort is sustained. According to the present embodiment, two types of the peak waves having differences in the width and the height are introduced, thereby eliminating the monotony of the airflow and achieving the comfort like natural wind. Here, two types of the peak waves having a difference only in the width or the height may be synthesized to the sine wave 131. Further, equal to or greater than three types of the peak waves may be synthesized to the sine wave 131.

In the present embodiment, the first peak waves 141 in each of which the time to reach the peak revolution speed is short and the peak revolution speed is high, and the second peak waves 142 in each of which the time to reach the peak revolution speed is long and the peak revolution speed is low are mixed. It has been confirmed by experiment and questionnaire evaluation that, as a result of the above, the comfort is improved, and the user can obtain the feeling of being exposed to natural wind.

To the sine wave 131, as large peak waves that occur some times in one cycle, the first peak waves 141, each having a width of around 5 to 10 seconds, each of which increases the revolution speed of the fan 102 by around 200 rpm is added. Further, as intermediate peak waves that occur some times in one cycle, the second peak waves 142, each having a width of around 10 to 20 seconds, each of which increases the revolution speed of the fan 102 by around 100 rpm is added. When the peak waves occur, the airflow speed at the user position is momentarily increased by around 0.4 to 0.8 m/s. Each of the large waves takes around 2 seconds to reach the peak value and maintains the same or close to the peak value for around 1 second. Each of the intermediate waves takes around 5 seconds to reach the peak value and maintains the same or close to the peak value for around 5 seconds. Therefore, the user can clearly feels a strong airflow corresponding to each of the large waves and an intermediate airflow corresponding to each of the intermediate waves.

In the present embodiment, the air conditioner 100 may have a function to select an airflow speed variation pattern in a natural mode from selectable patterns using the remote control 120. In this case, among the patterns, the sine wave 131 which is the reference waveform for the revolution speed waveform of the fan 102 may be different, the peak waves synthesized to the sine wave 131 may be different, or both of the sine wave 131 and the peak waves may be different. Or, the peak waves may be synthesized to the sine wave 131 at different time points of the sine wave 131. The control unit 118 receives information showing the pattern selected by the remote control 120 from the communication unit 117. The control unit 118 adjusts the revolution speed of the fan 102 based on the received information.

The air conditioner 100 may have a function to determine the user position using the sensor 109 and automatically adjust the air volume according to the distance to the user. In this case, the control unit 118 receives information showing a position of a human body from the sensor 109. The control unit 118 estimates a distance from the air conditioner 100 to the user based on the received information. The control unit 118 adjusts the revolution speed of the fan 102 according to the estimated distance. Specifically, the control unit 118 reads data from the table stored in the memory for each unit time. The control unit 118 multiplies the targeted revolution speed specified in the read data by a coefficient according to the estimated distance. The coefficient is, for instance, proportional to the distance. The control unit 118 controls the fan motor 116 so that the multiplication result and the revolution speed of the fan 102 match. Here, the control unit 118 may, instead of estimating the distance, determine an area in which the user exists out of areas inside the room. For instance, assume that the inside of the room is divided into the areas (e.g., 3 to 5 areas) in the depth direction. When the user exists in a rear area, the control unit 118 adjusts the revolution speed of the fan 102 upward. When the user exists in a front area, the control unit 118 adjusts the revolution speed of the fan 102 downward.

The air conditioner 100 may have a function to set the air volume step by step using the remote control 120. In this case, the average revolution speed of the fan 102 is not fixed but changeable. The control unit 118 receives information showing the air volume set by the remote control 120 from the communication unit 117. The control unit 118 adjusts the revolution speed of the fan 102 based on the received information. Specifically, the control unit 118 reads data from the table stored in the memory for each unit time. The control unit 118 multiplies the targeted revolution speed specified in the read data by a coefficient according to the level of the set air volume. The control unit 118 controls the fan motor 116 so that the multiplication result and the revolution speed of the fan 102 match. As a result, the airflow speed measured at a position which is 3 meters in front of the air conditioner 100 is changed. Further, a position at which the airflow speed is in the vicinity of 0.2 m/s is changed. Here, although the strength of the airflow changes, it remains unchanged that the user is to be provided with the feeling of being exposed to natural wind.

The air conditioner 100 may have a function to set ON/OFF of the natural mode in which the airflow similar to natural wind is delivered from the fan 102 using the remote control 120. In this case, the control unit 118 receives information showing ON/OFF of the natural mode from the communication unit 117. The control unit 118 adjusts the revolution speed of the fan 102 based on the received information. If a difference in the operating sound of the air conditioner 100 between the natural mode and a normal mode is large, the user may feel strange. Therefore, it is desirable that the variation range of the revolution speed of the fan 102 in one cycle of the sine wave 131 is equal to or less than a difference in the revolution speed between a case of setting the air volume at the maximum and a case of setting the air volume at the second maximum in the normal mode.

The air conditioner 100 may have a function to set ON/OFF of a swing mode to make the vertical air vanes 107 automatically swing using the remote control 120. In this case, the control unit 118 receives information showing ON/OFF of the swing mode from the communication unit 117. The control unit 118 starts or stops swinging of the vertical air vanes 107 based on the received information. Specifically, when the swing mode is ON and the natural mode is OFF, the control unit 118 makes the vertical air vanes 107 swing. That is, the control unit 118 continuously changes the angles of the vertical air vanes 107. On the other hand, when the swing mode is ON and the natural mode is ON or when the swing mode is OFF, the control unit 118 does not make the vertical air vanes 107 swing. That is, the control unit 118 fixes the angles of the vertical air vanes 107. If the vertical air vanes 107 swing while the control unit 118 continuously changes the air volume of the fan 102, the change of the airflow speed at the user position becomes different from what is intended. Therefore, when the natural mode is ON, the control unit 118 fixes the angles of the vertical air vanes 107 regardless of ON/OFF of the swing mode.

When the natural mode is ON, the control unit 118 may fix the angles of the left vertical air vane 107 a and the right vertical air vane 107 b in a way that the angles are different with each other. By keeping the angles of the left vertical air vane 107 a and the right vertical air vane 107 b from being aligned, two types of the airflow having different phases of the airflow speed variation can be delivered to the user. When two types of the airflow are mixed, the monotony of the airflow is further eliminated, and the naturalness of the airflow is increased. Further, by keeping the angles of the left vertical air vane 107 a and the right vertical air vane 107 b from being aligned, the range which the airflow reaches in the surface of the walls and the floor of the room is enlarged. If the airflow reaches a wider range, the airflow which bounces back from the surface of the walls and the floor is increased, and thus more airflow is delivered to the user. Therefore, the comfort is improved.

When the natural mode is ON, the control unit 118 may control the angles of the vertical air vanes 107 and the angles of the horizontal air vanes 108 so that the airflow from the fan 102 is directed to the position of the human body detected by the sensor 109. In this case, the control unit 118 receives information showing the position of the human body from the sensor 109. The control unit 118 determines an area in which the user exists out of areas inside the room based on the received information. For instance, assume that the inside of the room is divided into the areas (e.g., (3×3) to (5×5) areas) in the lateral and the depth directions. The control unit 118 adjusts the angles of the vertical air vanes 107 and the angles of the horizontal air vanes 108 toward the determined area.

As has been described, in the present embodiment, the control unit 118 controls the fan motor 116 so that the airflow speed of the fan 102 changes over time with the synthesis pattern composed of a plurality of patterns. The plurality of patterns include a sine-wave-like waveform pattern (e.g., the sine wave 131 of FIG. 5) and a hill-like variation pattern (e.g., the first peak waves 141 and the second peak waves 142 of FIG. 6) having a width (e.g., around 5 to 20 seconds) of less than a quarter cycle of the waveform pattern and a height (e.g., around 100 rpm or 200 rpm) of equal to or greater than the amplitude (e.g., 100 rpm) of the waveform pattern for each cycle (e.g., 120 seconds) of the waveform pattern. Therefore, the airflow having at least the characteristics of the previously-described (Characteristic 1) to (Characteristic 3) can be delivered from the fan 102, thereby providing the user with feeling of being exposed to natural wind.

Included as the variation pattern are two types of variation patterns (e.g., the first peak waves 141 and the second peak waves 142 of FIG. 6) of which the height and the occurrence timing in one cycle of the waveform pattern are different with each other. Therefore, the user does not get used to the strong airflow which comes once in a while, and thus the comfort is sustained.

The variation pattern (e.g., the first peak waves 141 of FIG. 6) having a higher height out of the two types of variation patterns reaches the maximum value in a shorter time than the variation pattern (e.g., the second peak waves 142 of FIG. 6) having a lower height. Therefore, the comfort like natural wind can be achieved.

The variation pattern maintains the maximum value for a certain period (e.g., around 1 second or 5 seconds). Therefore, the user can clearly feel the strong airflow which comes once in a while, and thus it becomes easier to provide the user with the feeling of being exposed to natural wind,

The control unit 118 previously stores, in a memory, control pattern information (e.g., a table) defining targeted revolutions of the fan 102 per predetermined unit time (e.g., 0.5 seconds) according to the synthesis pattern, and controls the fan motor 116 for each unit time based on the control pattern information.

The variation pattern maintains the maximum value for equal to or greater than two unit times (e.g., 1.0 second). Therefore, even if the fan motor 116 cannot follow the control at first, the revolution speed of the fan 102 finally reaches the peak targeted revolution speed, and thus the peak air volume can be certainly obtained.

A difference (e.g., 200 rpm) between the maximum value and the minimum value of the waveform pattern in one cycle is smaller than an average value (e.g., 800 rpm) of the waveform pattern in one cycle.

The control unit 118 may stop swinging of the vertical air vanes 107, if the vertical air vanes 107 are swinging, when starting an operation (e.g., the previously-described natural mode) to control the fan motor 116 so that the airflow speed of the fan 102 changes over time with the synthesis pattern.

The present embodiment can be applied to, not only the air conditioner 100, but also other air blowers such as an electric fan.

Embodiment 2

The present embodiment, in particular, a difference from the first embodiment will be described.

The configuration of the air conditioner 100 according to the present embodiment is the same as that of the first embodiment shown in FIGS. 1 to 4.

In the present embodiment, the control unit 118 continuously changes the revolution speed of the fan 102 so that the fan 102 delivers airflow having all the characteristics of the previously-described (Characteristic 1) to (Characteristic 4) at the time of the cooling operation or the air-blowing operation of the air conditioner 100.

In the present embodiment, the control unit 118 controls, similarly to the first embodiment, the fan motor 116 so that the sine wave 131 shown in FIG. 5 is the reference waveform for the revolution speed waveform of the fan 102.

In the present embodiment, similarly to the first embodiment, the variation range of the revolution speed of the fan 102 is small in one cycle of the sine wave 131. Therefore, as will be discussed later, wave components each having a narrow width and a low height can be synthesized to the sine wave 131 at many time points in one cycle of the sine wave 131.

FIG. 7 is a graph showing a revolution speed waveform of the fan 102.

As shown in FIG. 7, the control unit 118 controls, similarly to the first embodiment, the fan motor 116 so that first peak waves 141, each having a width of around 5 to 10 seconds and a height (i.e., the peak value) of around 200 rpm, and second peak waves 142, each having a width of around 10 to 20 seconds and a height (i.e., the peak value) of around 100 rpm, are synthesized to the sine wave 131. The first peak waves 141 are synthesized to the sine wave 131 at the time points of around 30 seconds, around 70 seconds, and around 110 seconds in one cycle of the sine wave 131. The second peak waves 142 are synthesized to the sine wave 131 at the time points of around 60 seconds and around 90 seconds in one cycle of the sine wave 131.

As described above, as for the waveform of natural wind speed, there frequently occurs a wave having a narrow width and a low height. The height of this wave is approximately the same every time. As shown in FIG. 7, the control unit 118 controls the fan motor 116 so that first random waves 151, each having a height of around 20 to 30 rpm, each of which is convex in the positive side and second random waves 152, each having a height of around 20 to 30 rpm, each of which is convex in the negative side are synthesized to the sine wave 131. The first random waves 151 are synthesized to the sine wave 131 at many time points so that the total width is equal to or greater than 10% and less than 50% of one cycle of the sine wave 131. The second random waves 152 are also synthesized to the sine wave 131 at many time points so that the total width is equal to or greater than 10% and less than 50% of one cycle of the sine wave 131. Not to degrade the effect of the peak waves, it is desired that the first random waves 151 and the second random waves 152 occur at the timing when there is no peak wave. Further, it is desirable that the number of occurrences of the first random waves 151 and the second random waves 152 are the same in one cycle of the sine wave 131.

If the height of the first random waves 151 and the second random waves 152 are equal to or greater than the amplitude of the sine wave 131, the airflow speed changes extremely frequently, and thus the user cannot easily obtain the feeling of being exposed to natural wind. In the present embodiment, the height of the first random waves 151 and the second random waves 152 are around 20 to 30 rpm, and the amplitude of the sine wave 131 (i.e., a half of the variation range of the revolution speed of the fan 102) is 100 rpm. Namely, the height of the first random waves 151 and the second random waves 152 are less than the amplitude of the sine wave 131. Therefore, minute and delicate airflow speed variation like natural wind is given to the airflow from the fan 102, thereby improving the comfort.

If the height of the first random waves 151 and the second random waves 152 exceed 40 rpm, the user may frequently and strongly feel the change of the airflow speed. Accordingly, the height of the first random waves 151 and the second random waves 152 should be preferably equal to or less than 40 rpm. However, if the height of the first random waves 151 and the second random waves 152 are too low, on the contrary to the above, the effect of the first random waves 151 and the second random waves 152 may be lost. Therefore, it is desirable that the height of the first random waves 151 and the second random waves 152 are equal to or greater than 20 rpm.

The control unit 118 stores, similarly to the first embodiment, a table specifying targeted revolution speeds of the fan 102 in the embedded memory. The control unit 118 supplies a command voltage to the fan motor 116 based on the table, thereby continuously changing the revolution speed of the fan 102.

As previously described, the table contains data specifying the targeted revolution speed of the fan 102 for each unit time. It is desirable to set one unit time to equal to or less than 1.0 second, with which the width of the first random waves 151 and the second random waves 152 can be reduced. For instance, assuming that the width of the first random waves 151 and the second random waves 152 are one unit time, the width of the first random waves 151 and the second random waves 152 are equal to or less than 1.0 second, thereby providing the airflow from the fan 102 with the minute airflow speed variation.

According to the present embodiment, it is possible to provide the airflow from the fan 102 with the minute airflow speed variation that might be or might not be sensed by the user. As a result, monotony of the airflow can be avoided. Further, the minute airflow speed variation occurs frequently, thereby reducing the operating noise of the fan 102 at the time of accelerating or decelerating.

FIG. 8 is an enlarged graph showing a part of FIG. 7.

As shown in FIG. 8, each of the first peak waves 141 increases its value in two or more stages to reach the maximum value (i.e., the peak value) from the sine wave 131, which is the reference waveform.

Assuming that each of the peak waves increases its value in only one stage to reach the maximum value, the acceleration sound of the fan 102 would be large, and thus the comfort would be degraded. For instance, if the revolution speed of the fan 102 is increased by equal to or greater than 130 rpm in 1 second through one stage, a harsh sound is generated. Further, if the airflow speed is increased at once and decreased immediately after that, the user does not easily feel the change of the airflow speed, and thus the effect of the peak waves might not be obtained.

On the other hand, if each of the peak waves increases its value in two or more stages to reach the maximum value, the acceleration speed of the fan 102 is decreased, thereby suppressing the generation of the harsh sound. Further, since the user easily feels the change of the airflow speed, the effect of the peak waves can be certainly obtained.

Between the increase in the first stage and the increase in the second stage, the airflow speed may be momentarily decreased, or may be unchanged. The same can be said for the increase in the subsequent stage(s). The time required for the increase in each stage may be short; the time is equal to or less than 10 seconds, and more preferably, equal to or less than 5 seconds. Further, if it is assumed that the time required for the increase in each stage is set to equal to or greater than two unit times, or equal to or greater than 0.5 seconds, it is considered that the user can clearly feel the change of the airflow speed in each stage.

As has been described, in the present embodiment, the control unit 118 controls, similarly to the first embodiment, the fan motor 116 so that the airflow speed of the fan 102 changes over time with the synthesis pattern composed of a plurality of patterns. The plurality of patterns include, in addition to the sine-wave-like waveform pattern (e.g., the sine wave 131 of FIG. 5) and the hill-like variation pattern (e.g., the first peak waves 141 and the second peak waves 142 of FIG. 7), a hill-like first added pattern (e.g., the first random waves 151 of FIG. 7) having a height (e.g., 20 rpm to 30 rpm) of less than the amplitude (e.g., 100 rpm) of the waveform pattern for each cycle (e.g., 120 seconds) of the waveform pattern, of which the occurrence timing in one cycle of the waveform pattern is different from the variation pattern. The plurality of patterns further include a valley-like second added pattern (e.g., the second random waves 152 of FIG. 7) having a height of less than the amplitude of the waveform pattern for each cycle of the waveform pattern, of which the occurrence timing in one cycle of the waveform pattern is different from the variation pattern and the first added pattern. Therefore, the airflow having the characteristics of the previously-described (Characteristic 1) to (Characteristic 4) can be delivered from the fan 102, thereby providing the user with feeling of being exposed to natural wind.

The variation pattern increases its value in two or more stages to reach the maximum value. Therefore, the acceleration sound of the fan 102 can be reduced. Further, since the user easily feels the change of the airflow speed, the effect of the variation pattern can be certainly obtained.

In the foregoing, the embodiments of the present invention have been explained; two or more of these embodiments may be combined and implemented. Or, one of these embodiments may be implemented partially. Or, two or more of these embodiments may be partially combined and implemented. Here, the present invention is not limited to these embodiments, but can be modified in various ways as necessary.

Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the disclosure of this patent specification may be practiced otherwise than as specifically described herein.

REFERENCE SIGNS LIST

100: air conditioner; 101: main body; 102: fan; 103: pre-filter; 104: front panel; 105 a: first heat exchanger; 105 b: second heat exchanger; 105 c: third heat exchanger; 105 d: fourth heat exchanger; 106: drain pan; 107, 107 a, 107 b: vertical air vanes; 108, 108 a, 108 b: horizontal air vanes; 109: sensor; 110: air inlet; 111: air outlet; 112 a, 112 b, 114 a, 114 b: link rods; 113 a, 113 b, 115 a, 115 b: stepping motors; 116: fan motor; 117: communication unit; 118: control unit; 120: remote control; 131: sine wave; 141: first peak waves; 142: second peak waves; 151: first random waves; and 152: second random waves. 

1. An air blower comprising: a fan blowing air; a fan motor driving the fan; and a control unit controlling the fan motor so that an airflow speed of the fan changes over time with a synthesis pattern composed of a plurality of patterns including a sine-wave-like waveform pattern and a hill-like variation pattern having a width of less than a quarter cycle of the waveform pattern and a height of equal to or greater than an amplitude of the waveform pattern for each cycle of the waveform pattern.
 2. The air blower of claim 1, wherein the plurality of patterns include, as the variation pattern, two types of variation patterns of which height and occurrence timing in one cycle of the waveform pattern are different with each other.
 3. The air blower of claim 2, wherein the variation pattern having a higher height out of the two types of variation patterns reaches a maximum value in a shorter time than the variation pattern having a lower height.
 4. The air blower of claim 1, wherein the variation pattern increases a value in two or more stages to reach a maximum value.
 5. The air blower of claim 1, wherein the variation pattern maintains a maximum value for a certain time period.
 6. The air blower of claim 1, wherein the plurality of patterns further include a hill-like first added pattern, having a height of less than the amplitude of the waveform pattern for each cycle of the waveform pattern, of which occurrence timing in one cycle of the waveform pattern is different from the variation pattern, and a valley-like second added pattern, having a height of less than the amplitude of the waveform pattern for each cycle of the waveform pattern, of which occurrence timing in one cycle of the waveform pattern is different from the variation pattern and the first added pattern.
 7. The air blower of claim 6, wherein a number of occurrences of the first added pattern and a number of occurrences of the second added pattern are same.
 8. The air blower of claim 1, wherein the control unit previously stores, in a memory, control pattern information defining targeted revolutions of the fan per predetermined unit time according to the synthesis pattern, and controls the fan motor for each unit time based on the control pattern information.
 9. The air blower of claim 8, wherein the variation pattern maintains a maximum value for equal to or greater than two unit times.
 10. The air blower of claim 8, wherein one unit time is equal to or greater than 0.1 seconds and equal to or less than 1.0 second.
 11. The air blower of claim 1, wherein a difference between a maximum value and a minimum value of the waveform pattern in one cycle is smaller than an average value of the waveform pattern in one cycle.
 12. The air blower of claim 1 further comprising: vertical air vanes provided so as to be swingable and adjusting a vertical direction of airflow from the fan, wherein the control unit stops swinging of the vertical air vanes, if the vertical air vanes are swinging, when starting an operation to control the fan motor so that the airflow speed of the fan changes over time with the synthesis pattern.
 13. The air blower of claim 12, wherein the vertical air vanes are divided into a left vertical air vane and a right vertical air vane, and wherein the control unit, when carrying out the operation, fixes angles of the left vertical air vane and the right vertical air vane in a way that the angles are different with each other.
 14. The air blower of claim 12 further comprising: horizontal air vanes adjusting a horizontal direction of the airflow from the fan; and a sensor detecting a position where a human body exists, wherein the control unit, when carrying out the operation, controls angles of the vertical air vanes and angles of the horizontal air vanes so that the airflow from the fan is directed to the position detected by the sensor.
 15. A control method comprising: controlling a fan motor which drives a fan, so that an airflow speed of the fan changes over time with a synthesis pattern composed of a plurality of patterns including a sine-wave-like waveform pattern and a hill-like variation pattern having a width of less than a quarter cycle of the waveform pattern and a height of equal to or greater than an amplitude of the waveform pattern for each cycle of the waveform pattern. 